The proposed research will be aimed toward understanding those factors, cultural, biochemical, and genetic which regulate the synthesis of sterols. Esterification of sterols, the role of esters in sterol metabolism, and nature of intermediate forms in sterol biosynthesis will be investigated. The wild-type yeast, Saccharomyces cerevisiae, and several mutants will be used in the study. BIBLIOGRAPHIC REFERENCES: R.B. Bailey and L.W. Parks, 1975. Potassium translocation in yeast mitochondria and its relationship to ergosterol biosynthesis. J. Bacteriol. 122, 606. R.B. Bailey, L. Miller, and L.W. Parks, 1976. Enzymic analysis of C-27-sterol accumulating yeast strains. J. Bacteriol. 126, In press.